Technology

How passive radiative cooling works.

SkyRad combines high solar reflectance with thermal emission through the 8–13 μm atmospheric window — a wavelength range where heat can escape toward the cold sky.

Atmospheric window

The sky is a heat sink.

At specific infrared wavelengths, the atmosphere is relatively transparent. This allows thermal radiation from engineered surfaces to move outward rather than being trapped near the building.

Atmospheric transmission window chart highlighting 8 to 13 micrometers
Conceptual chart: thermal emission pathway through the 8–13 μm window.

Why coating design matters

Ordinary white coatings reflect visible light, but a radiative cooling surface must also emit strongly in the mid-infrared. The combination of reflectance and emissivity is what creates passive cooling potential.

  • High solar reflectance to reduce absorbed heat
  • High mid-infrared emissivity for heat rejection
  • Durable retrofit layer for exposed roofs

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